Protein Domain : NADH-ubiquinone oxidoreductase, 20 Kd subunit IPR006138

Type	Family
Description	NADH:ubiquinone oxidoreductase (complex I) ( ) is a respiratory-chain enzyme that catalyses the transfer of two electrons from NADH to ubiquinone in a reaction that is associated with proton translocation across the membrane (NADH + ubiquinone = NAD+ + ubiquinol) [ ]. Complex I is a major source of reactive oxygen species (ROS) that are predominantly formed by electron transfer from FMNH(2). Complex I is found in bacteria, cyanobacteria (as a NADH-plastoquinone oxidoreductase), archaea [], mitochondria, and in the hydrogenosome, a mitochondria-derived organelle. In general, the bacterial complex consists of 14 different subunits, while the mitochondrial complex contains homologues to these subunits in addition to approximately 31 additional proteins [].Among the many polypeptide subunits that make up complex I, there is one with a molecular weight of 20kDa (in mammals) [ ], which is a component of the iron-sulphur (IP) fragment of the enzyme. It seems to bind a 4Fe-4S iron-sulphur cluster. The 20kDa subunit has been found to be nuclear encoded, as a precursor form with a transit peptide in mammals, and in Neurospora crassa. It is mitochondrial encoded in Paramecium (gene psbG) and chloroplast encoded in various higher plants (gene ndhK or psbG).
Short Name	NADH_UQ_OxRdtase_20Kd_su